Over-end winding of yarn



United States Patent U.S. Cl. 57156 4 Claims ABSTRACT OF THE DISCLOSUREPatterning in a yarn package, due to e.g. ring-tilt, is reduced byvarying the spindle speed at more than one frequency of variation.

The invention concerns improvements in or relating to the over-endwinding of yarn.

Over-end winding of yarn, as on the well-known ring spinning machine ,ispractised when it is desired to impart a twist to the yarn by the act ofwinding.

A common instance of such over-end winding is to be found in thedrawtwisting of synthetic polymer filaments; and the present inventionwill be described in relation to such drawtwisting, although it is to beunderstood that the invention is not limited thereto.

A drawtwister is essentially a downtwister in which are incorporatedroll mechanisms for drawing undrawn yarn. Usually, such mechanismsconsist of nip rolls rotated at a given speed acting as feed rolls; anda draw roll and separator roll combination, the former roll of which isrotated at the required higher speed to effect the drawing action on thefilaments in question. From the draw roll, the drawn filaments proceedin a generally downward direction to a thread guide positioned axially,or nearaxially, of the spindle of a ring and traveller ring spinningmechanism. This thread guide is sometimes known as the balloon guide, asthe yarn is ballooned beneath it by virtue of the rotation of thetraveller around the ring. The filaments are then wound up on a bobbinmounted on the rotating spindle, by passage around the traveller whichis itself rotated around the ring and by reciprocation of the ring, inits rail, tray or other carrier, in the axial direction of the spindleaccording to the builder motion required for the particular yarn packageto be wound on the bobbin.

It is a quite usual artifice to tilt the ring of the ring spinningmechanism in order that the filaments shall be laid on to the bobbin andyarn package in helical coils having a wavy path rather than a flathelical one. An angle of tlit of between 3 and 6 is usual; although anangle even as low as 1 may be selected and will donate an appreciablewave component to the laying-on path of the yarn. Rings are notgenerally set to a greater degree of accuracy than within /2".

Such ring tilt is at least a major factor predisposing the formation ofregions of patterning at certain radii of the package build, owing tothe coincidence of adjacent coil loci. The incidence of these variousregions of patterning, which patterning is to be avoided both from thetechnical point of view of package stability and yarn take-01fcharacteristics and from the point of view of appearance, can becalculated, e.g. by analogue computer, for any given process involving adrawtwisting wind-up; and hence it is possible to so programme thewinding conditions that the regions of patterning which normally wouldoccur shall be avoided.

3,452,533 Patented July 1, 1969 An alternative, or concomitant, approachto the reduction or avoidance of patterning, whether from natural orself-induced causes, consists in the rapid variation of one or more ofthe winding parameters, to bring about a scrambling of the windingconditions throughout the winding, in order continuously to modify thewave-form of the coils of yarn as laid on to the take-up package.

Thus, the spindle speed may be rapidly varied by, say, 10% about themean value desired; and this rapid variation, or scrambling, of thespindle speed will serve to break up patterning when it occurs at thecalculable winding conditions during the formation of the package.Variation takes place in a cyclical manner about the mean spindle speed;and the number of cycles occurring in unit time is termed herein thefrequency.

We have found, however, that with one fixed frequency of speed variationfor the spindle speed, there is the disadvantage with constant-ratetraverse motions that conditions will recur during the winding when theratio of spindle speed scrambling frequency to traverse frequency is aratio of small whole numbers such as to lead, of itself, to patterningregions throughout large volumes of the package.

The present invention, therefore, is based on the proposition that marethan one spindle speed scrambling frequency shall be employed during thewinding, the choice of frequencies and the programming of theirapplication being effected so as to avoid any ratio of scramblingfrequency to traverse frequency during the entire winding which is aratio of small whole numbers leading of itself to patterning.

The invention comprises a method of winding yarn by over-end winding onto a package with the aid of a rotating spindle and a traversing means,wherein the speed of rotation of the spindle is varied cyclically aboutmean values thereof selected to be operative at given times during thewinding of the package, or about a mean such value maintained constantthroughout the winding, and wherein the frequency of such cyclicalvariation in spindle speed is changed between at least two values duringthe winding, according to a programme of changes calculated to avoid anyvalue of the ratio of said frequency to the traversing frequency everbeing one consisting of small whole numbers (i.e. either of which isless than 5) such as would of itself lead to patterning occurring atgiven radii of the package during winding.

Whilst it is possible to effect an improvement compared with a singlespindle speed variation cycle time by the use of two such cycle times,it is not always possible completely to disperse regions of patterningthereby. This is because, although the shifting of such scramblingfrequency has the effect of enabling whole-number ratios of scramblingfrequency to traverse frequency to be avoided, nevertheless it also hasthe effect of changing the width and spacing of regions of patterningcaused thereby, making it difificult to so alternate two frequenciesthat shift from one to the other does not involve a shift into part of aregion of patterning.

Hence, it is preferred, according to the invention, to use more than twoscrambling frequencies, whereby the chance of programming the shifts soas completely to avoid patterning conditions is greatly enhanced.

The means of programming may take various forms, the exact operation ofwhich may depend on whether the traverse motion of the drawtwistingmachine is of a constant-rate or a constant-time variety.

Programming by a general purposes analogue computer is one such means,the computer serving automatically to control the number of changes inspindle speed cycle time occurring during the winding of a full package,by continuously measuring said traverse cycle by electronic means andcontrolling shifts from one frequency to another so as to avoid thecritical ratios of such scrambling frequency to traverse frequency.

The specific method of shifting spindle speed cycle times according tothe invention, e.g. by regulation of a servomotor in the spindle drivingmechanism, may be combined with other expedients for the avoidance orreduction of patterning in overend wound yarn packages.

Thus, the invention may be combined with other more radical programmingof the spindle speed, e.g. whereby regions of patterning due to ringtilt may be avoided. Equally, the invention may be combined withcontrolled or random variations in traveller speed and with yarndelivery speed.

Whilst the invention is applicable to the winding of yarn packages onall kinds of bobbin or tube, it will be understood that the particularprogramme to be selected will be affected by the shape of the tube, e.g.as to whether it is frusto-conical or cylindrical.

By way of one example of the invention, the following details are givenof a process for drawtwisting 70 denier 30 filament yarn ofpolyhexamethylene adipamide (nylon 66), at a draw ratio of 3.36 and adrawing speed of 2,300 feet/minute. The yarn was woundup by a ringspinning mechanism with the ring tilted to 3 to the horizontal; and theyarn package was wound with a long-to-short traverse build, constanttraverse speed. The spindle speed was programmed so as to reduce from aninitial 9,750 r.p.m. to a final speed of 7,350 r.p.m.

In addition to the above programming, a 3-shift rapid variation inspindle speed was programmed on to the spindle drive mechanism by ananalogue computer, of an amplitude of of the instant spindle speed, therate of change of spindle speed (or scrambling frequency) being changedaccording to a 3-shift rapid variation programme so designed that theshifts in spindle speed occurred when the ratio of scrambling frequencyto traverse frequency at one of the scrambling frequencies approached aratio of small whole numbers, i.e. whole numbers either of which is lessthan 5.

In a second, but less advantageous example of the invention, 100 denier34 filament yarn of polyhexamethylene adipamide was wound up at 2646feet/minute after being drawn on a drawtwisting machine. The yarn waswound-up by a ring spinning mechanism, with the ring tilted to 3 to thehorizontal; and the yarn package was wound with a long-to-short traversebuild, at a constant traverse speed of 23 inches/minute. The meanspindle speed was maintained constant at 6,850 r.p.m.; and this speedwas varied -10% about the mean at two discrete frequencies, and a changewas made from one to the other, at the lengths of traverse stroke asshown in the following table:

In the above case, the high value of 0.048 cycle/second was selected inorder to place the 1:1 ratio of scrambling frequency to traversefrequency just outside the range of package build. Then, the lowerfrequency of 0.03 84 cycle/second was selected in order to avoid theoccurrence of an undistributed patterned region near to the bobbinsurface, where pressures are greatest within the package.

Although an amplitude of 10% is exemplified above for the variation inspindle speed, it will be understood by those skilled in the art that,as the severity of patterning in the various regions of it will not beuniform through the package, a lesser amplitude, sa-y 3%-4%, may beadequate to disperse the patterning in certain of the regions; and thus,if the package is wound in such manner as to avoid the occurrence ofpatterning of the most severe nature, it may be possible, according tothe invention, to employ such a lesser amplitude of spindle speedvariation.

Likewise, it is within the scope of the invention to change theamplitude according to a programme, whereby the higher amplitudes areselected at those times during the winding when calculation hasdetermined that regions of severe patterning will take place, and loweramplitudes are selected for the other calculated regions.

The principle, so far as amplitude is concerned, is to use the lowestamplitude consonant with the achieving of effective dispersion of thepatterns; so that amplitudes greater than, say 15% will be unlikely tobe needed or desirable.

We are aware of our co-pending application Ser. No. 661,771, filed oneven date herewith which discloses the continuous monitoring and controlof spindle speed scrambling frequency by, and directly in relation to,the traverse frequency.

We claim:

1. 'In the method of winding yarn by over-end winding on to a packagewith the aid of a rotating spindle and a traversing means, in whichmethod the speed of rotation of the spindle is varied cyclically aboutthe desired mean value during the winding of the package, theimprovement comprising switching the frequency of such cyclicalvariation in spindle speed between at least two values, as the ratio ofsaid frequency to the traversing frequency approaches values giving riseto any substantial degree of patterning, in a manner to avoid any valueof said ratio ever being one consisting of small whole numbers either ofwhich is less than 5 whereby regions of patterning in the package areavoided.

2. A method according to claim 1 in which the amplitude of said cyclicalvariation in spindle speed is between 3% and 15 of the instant meanspindle speed.

3. A method according to claim 2 in which said amplitude is itselfchanged according to a programme during the period of winding.

4. A method as in claim 1 including the step of electronicallymonitoring the traverse cycle to obtain a signal and wherein thefrequency of the cyclical variation in spindle speed is switched inaccordance with a function of said signal.

References Cited UNITED STATES PATENTS 2,658,689 11/1953 Waldrop 24218.l3,137,987 6/1964 Potts 5755.5 3,235,191 2/1966 Engelman 242-l8.l3,241,779 3/1966 Bray et al. 24218.1 3,325,985 6/1967 Bucher 242-26.3 XR

JORDAN FRANKLIN, Primary Examiner.

WERNER H. SCHROEDER, Assistant Examiner.

US. Cl. X.R. 57-93; 242-181

